OMG!
When the fish is NOT active, immediately medicate her water and isolate her from other fish!! The kulat/dust thing is a kind of fungus, VERY CONTAGIOUS..
NEVER mix the sick fish with another healthy fish..

You know, one should do some research BEFORE even attempting to breed anything.. BEFORE thinking of BREEDING, think of how to take care of the fish 1ST.. Make sure u can keep the fish in the fittest, healthiest condition first.. That is of utmost importance.. Breeding is secondary, pls don't play around with the poor fishes...

From my experience, once any fish has the kulat/dust/fungus, it is 95% incurable, even with the strongest anti-fungus solution I could find. Most of my fishes who gets it don't recover, even the healthiest would only fight the illness for a week or so before they die very very very slowly.

In short, PLS TC of your fish - they must be ACTIVE and HEALTHY and EAT LIKE A PIGGY .. before you even think of breeding. Your lack of knowledge regarding these poor Bettas scare me. 

hehe. you know, i only saw your post today but tell you la......... i just bought 2 bettas on Monday.

no la. costly.
mana bite dust. i kept betta long time already la just stopped keeping them for the past 3 - 4 years only.

you can ask yewlin. nearly bought from him also last time.

just that nowadays i was fixing up many of my other tanks, decided to start again - which is why i come by this thread once a while, cos i memang betta fan for long time already.

just that now, no more playing CT / HM. i prefer PK / HM PK / ST.

one thing about betta la, no worth you spend the $$$ on them unless you are going to do breeding and have the commitment to do so.

for me, my RM 3 types also I'm happy already.

a lot of people keep betta for the tail.

actually for me la. i keep them more for their character.

put them in a bigger tank and see how they move around and explore the place, it's very interesting.

if not also when you come near, the fella will come to you like say "hello" then go back doing his things.